The mere fact that the man had been stabbed from behind and to the heart, precluded any possibility of his having jumped up and caught at the back of the chair afterwards.

Placing my left hand upon the back, I clasped my fingers under the piece of wood above-mentioned, to discover that a portion of the second finger fell exactly upon the stain.
"Now I think I understand the situation," I said to myself.

"The old man was seated at the table, about to commence his meal, when the murderer entered very quietly by the door behind him.

He rested his left hand upon the chair to steady himself while he aimed the fatal blow with his right." But in that case how did the knife touch the middle finger of his left hand?
From the fact that the body was discovered lying upon its back just as it had fallen, and that the chair was also still upon the floor, it was evident that the blood must have got there before, not after, the crime was committed.

Leaving the room I went out to the yard at the back and studied the paling fence.